1. Field of the Invention
The present invention relates to a speaker device and a speaker-excitation method, and particularly relates to a speaker device and a speaker-excitation method that are provided so that a displacement output of an actuator is transferred to a point predetermined on the face of an acoustic diaphragm via a displacement-output-transfer member and the acoustic diaphragm is excited from the predetermined point in the face direction according to the displacement output of the actuator, which makes it possible to obtain a sound image with a feeling of spaciousness, obtain a sound output faithful to a sound signal, and increase flexibility in selecting the shape of the acoustic diaphragm.
2. Description of the Related Art
Heretofore, sound-output devices configured to obtain a sound output by driving a diaphragm by using a magnetostrictive actuator have been known, as disclosed in Japanese Unexamined Patent Application Publication No. 4-313999. The magnetostrictive actuator is an actuator using a magnetostrictive element, where the shape of the magnetostrictive element is changed due to an external magnetic field given thereto.
FIG. 19 shows an example configuration of a sound-output device 300 including a magnetostrictive actuator 303. The sound-output device 300 includes a player 301, an amplifier 302, the magnetostrictive actuator 303, and a diaphragm 304. Here, the magnetostrictive actuator 303 and the diaphragm 304 generate a speaker device 305.
The player 301 reproduces data recorded onto a compact disk (CD), a mini disk (MD), a digital-versatile disk (DVD), etc., for example, and outputs a sound signal. The sound signal output from the player 301 is amplified by the amplifier 302, and transmitted to the magnetostrictive actuator 303. The magnetostrictive actuator 303 includes a drive rod 303a configured to transfer a displacement output. The tip of the drive rod 303a abuts the diaphragm 304.
The magnetostrictive actuator 303 drives the diaphragm 304 based on the sound signal. Namely, the drive rod 303a of the magnetostrictive actuator 303 is displaced according to the waveform of the sound signal, and the signal of the displacement is transferred to the diaphragm 304. Subsequently, it becomes possible to obtain the sound output corresponding to the sound signal from the diaphragm 304.